The present invention relates to an improved recovery process for coated and/or uncoated, plasticized regenerated cellulose film waste. More particularly, such waste regenerated cellulose film is treated to reclaim the regenerated cellulose as a viscose solution and the plasticizer as an aqueous solution thereof, suitable for recycling in the production of new generated cellulose film.
"Waste" regenerated cellulose (popularly called cellophane) film, including both coated and uncoated film, is generated at several stages in the manufacture and finishing of such film. The amounts of waste regenerated cellulose film produced relative to the total film production is not insignificant, so both economic and disposal considerations provide an impetus towards recovery and/or recycling of the regenerated cellulose and other valuable components of the waste film. A representative coated regenerated cellulose film consists of three major components: regenerated cellulose constituting the film; plasticizer which imparts flexibility to the film; and one or more coating compositions on one or both surfaces of the film.
Methods proposed in the prior art for regenerated cellulose recovery are characterized by many complex process steps and operations, often involving the use of various solvents for selectively extracting each of the waste film components.
U.S. Pat. No. 3,758,457 issued to TenBroeck et al. discloses a method for recovering regenerated cellulose from coated waste cellophane film, wherein softener and coating materials are removed from the comminuted cellophane with solvents. The softener is first selectively extracted from the comminuted cellophane with a solvent, but the softener must then be recovered via distillation of the softener-insolvent extract before the softener can be reused in the manufacture of cellophane film. This comminuted cellophane is dried to remove traces of the softener extraction solvent, afer which the coating is extracted using a solvent that dissolves the coating from the comminuted cellophane. The comminuted cellophane is thereafter again dried and may be employed as recycle material, by its conversion to viscose solution, in the manufacture of regenerated cellulose film.
An improved means for removing the residual coating extraction solvent from the comminuted cellophane in the TenBroeck et al. method is taught in U.S. Pat. No. 3,884,907 issued to Laurance et al., but this invention does not reduce the complexity or the number of individual process steps of the TenBroeck et al. method.
While the prior art methods provide one approach for recovering regenerated cellulose and other major components from waste cellophane film, a simplified recovery process is desirable because of the complexity and number of process operations required in such methods. Fewer process steps may usually be translated into reduced equipment, labor and time requirements, and savings on or elimination of some ancillary raw materials (e.g., extraction solvents, steam).